I have my passport because of work. I've been to Toronto about a half dozen times for work, so I know I need it to fly. Right now, I've been told, to drive, all you need is a photo ID. What about a year from now? Will we need passports then? I am trying to get some info for my group.
To follow up for Yankee attendance: There were quite a few that I met and a lot of cars with New York, Michigan, and Ohio License plates in the parking lot. However, it was held at a hotel, and there was also a Ford Model T enthusist convention going on at the same time. So it's a little hard to gauge.
If you went next year, you wouldn't be the only American, that's for sure!